Preparation of explosive nitric ester gels

ABSTRACT

A PROCESS FOR THE PREPARATION OF AN EXPLOSIVE COMPOSITION CONTAINING NITROCELLULOSE AND AN EXPLOSIVE NITRIC ESTER, SUCH AS NITROGLYCERINE. THE NITROCELLULOSE IS FIRST MIXED WITH A LIQUID DISPENSING AGENT, SUCH AS ETHYLENE GLYCOL AND/OR GLYCERINE, AND THEREAFTER MIXED WITH THE EXPLOSIVE NITRIC ESTER.

United States Patent OflEice 3,736,196 Patented May 29, 1973 3,736,196 PREPARATION OF EXPLOSIVE NITRIC ESTER GELS Gordon M. Gay, Tacoma, Wash., assignor to Commercial Solvents Corporation, Terre Haute, Ind. No Drawing. Filed Feb. 24, 1971, Ser. No. 118,507 Int. Cl. C06b 1/04 US. Cl. 149-48 3 Claims ABSTRACT OF THE DISCLOSURE A process for the preparation of an explosive composition containing nitrocellulose and an explosive nitric ester, such as nitroglycerine. The nitrocellulose is first mixed with a liquid dispersin agent, such as ethylene glycol and/or glycerine, and thereafter mixed with the explosive nitric ester.

The present invention generally relates to the preparation of explosive nitric ester gels and more particularly to the preparation of gels of nitrocellulose and nitroglycerine for explosives use.

Gels of nitrocellulose and nitroglycerine are routinely used in making explosive compositions, such as relatively low sensitivity powders and dynamites.

In my copending US. patent application Ser. No. 861,- 490, filed Sept. 26, 1969, there is described a water-bearing slurry explosive composition containing nitroglycerine and nitrocellulose in which the nitroglycerine is pregelled with nitrocellulose. Combinations of nitrocellulose and nitroglycerine are also used in the Well-known ammonia gelatin dynamites and gelatin dynamites. In the gelatin dynamites the gel portion, in fact, is nitroglycerine gelled with nitrocellulose. So-called blasting gelatins contain relatively high percentages of nitrocellulose and nitroglycerine.

However, when nitroglycerine and nitrocellulose are mixed, so-called nitrocotton lumping is conventionally obtained, and, of course, lumps are undesirable because their use would cause the resultant product to be more sensitive than is desirable.

It is an object of the present invention to provide a process for preparing a uniform gel of nitrocellulose and nitroglycerine.

These and other objects and advantages of the present invention will be understood from the description of the invention.

In accordance with the present invention a uniformly smooth gel of nitrocellulose and nitroglycerine is obtained when the nitrocellulose is mixed with a liquid dispersing agent, preferably ethylene glycol and/or glycerine prior to mixing with the nitroglycerine.

The explosive nitric ester gel preparation of this invention is, accordingly, prepared from at least three ingredients; namely,

(a) nitrocellulose, (b) liquid dispersing agent, and (c) explosive nitric ester.

Each of these will now be more specifically described.

(a) Nitrocellulose Nitrocellulose is an ingredient very commonly employed in the explosive industry. Various types and grades are available and the term as used herein includes all types and grades including, inter alia, nitrocotton and nitrostarch.

The nitrocellulose is used in an amount sufiicient to gel (c) the explosive nitric ester. Preferably the nitrocellulose is used in amount of from about 0.5% to about 3% by weight of the explosive nitric ester gel product of the process of this invention. As hereinbefore stated, the explosive nitric ester gel of this invention is 'most usually used as an ingredient in the preparation of explosive compositions such as dynamites, explosive slurries and blasting gelatins. When the weight percent of nitrocellulose is based, the weight of such explosive compositions, the nitrocellulose is generally used in amount of from about 0.05% to about 8.0% of the final explosive composition. For explosive gels the range is preferably from about 0.1% to about 6%. For explosive slurries the preferred range is from about 0.2% to about 1%.

(b) Liquid dispersing agent The liquid dispersing agent may be ethylene glycol or glycerine or ethylene glycol-glycerine mixtures. Ethylene glycol and glycerine appear to be completely miscible in all proportions and are included within the scope of this invention. Water solutions of ethylene glycol, glycerine. and ethylene glycol-glycerine mixtures are also suitable; typical solutions having a weight percent of water of from about 10% to about 50%.

The liquid dispersing agent is used in amount of from about 5% to about 15% by weight of the explosive nitric ester gel. When the weight percent of the liquid dispersing agent is based on the more typical final explosive composition, the amount is generally from about 1% to about 5%.

(c) Explosive nitric ester nitric ester is commonly used to refer to such explosive materials. Nitrated mixtures of 35% glycerol and 65% ethylene glycol by weight are typical.

The explosive nitric ester is used in amount of from about to about by weight of the explosive nitric ester gel product. When the weight percent of the explosive nitric ester is based on the more typical final explosive composition, the amount is generally from about 5% to about 25%, preferably from about 6% to about 20%.

It is well known to gel (c) nitroglycerine with (a) nitrocotton or other nitrocellulose material. In general the pregelling requires from about 1 to about 10 minutes; however, longer times may be used.

Pregelling of the nitroglycerine, or other liquid explosive ester, effectively immobilizes the nitroglycerine; that is, the pregelling with the nitrocellulose prevents the liquid nitroglycerine from migrating in the explosive composition and collecting in dangerous amounts.

In accordance with the present invention, the nitrocellulose is first miXed with (b) a liquid dispersing agent. This mixing may be done in conventional explosives mixing equipment or the liquid dispersing agent may be sprayed or atomized onto the nitrocellulose. The purpose is, of course, to obtain relatively uniform distribution of the liquid dispersing agent in the nitrocellulose.

When the (a) nitrocellulose- (b) liquid dispersing agent mixture is then mixed with the liquid explosive nitric ester in amount to gel the ester, as hereinbefore set forth, there is much less tendency for the nitrocellulose to ball and, therefore, the explosive nitric ester gel is more uniform in composition. Such a uniform explosive nitric ester gel may, of course, also be more readily mixed with the other ingredients used in preparing convention explosive products such as dynamites, slurries and explosive gels.

The following examples, in the opinion of the inventor, represents the best embodiments of the invention.

3 EXAMPLE 1 An explosive aqueous slurry composition is prepared as follows:

Nitrocotton (0.2 lb.) is mixed with ethylene glycol (1.0 lb.) for 1 minute. The mixture and nitroglycerine (14.0 lbs.) are mixed for 5 minutes to form a relatively uniform thick gel. The nitroglycerine used is a nitrated mixture of 65% ethylene glycol and glycerine.

A dope mix is prepared by intimately admixing the following ingredients.

Ingredient: Lbs. Starch 2.5 Fine sulfur 1.0 Coal (20 mesh) 2.0 Fine grain ammonium nitrate 54.00 Fine ground sodium nitrate 11.80 20 mesh coal 2.00 T-14 pulp 0.50 Chalk 1.00

One-third of the dope mix is added to the 15.2 lbs. of the nitrocotton-ethylene glycol-nitroglycerine gel and is mixed for 1 minute.

After 1 minute of mixing. 10.0 lbs. of water at 135 F. is added and mixed for 1 minute. The remainder of the dope mix and 2.00 lbs. cross-linked guar gum are then added and mixed for an additional 6 minutes. The re sultant aqueous slurry was tested in a 1%" x 16" cartridge and was not detonatable by a No. 6 electric blasting cap. The cartridge was detonated by a 0.25 lb. booster and the unconfined detonation was l5.000-l6,000 feet/ second. The rate of detonation confined was 18,000- 19,000 feet per second. The density of the product was 1.56 grams/cc. The water resistance of the product was rated as excellent.

EXAMPLE 2 Ingredient: Lbs. Starch 2.5 Fine sulfur 1.5 Coal (20 mesh) 3.0 Fine grain ammonium nitrate 56.00 Fine ground sodium nitrate 10.80 20 mesh coal 3.00 Chalk 1.00

One-third of the dope mix is added to the 13.2 lbs. of the nitrocotton-ethylene-glycol-nitroglycerine gel and is mixed for 1 minute.

After 1 minute of mixing. 10.0 lbs. of water at 135 F. is added and mixed for 1 minute. The remainder of the dope mix and 2.00 lbs. of cross-linked guar gum are then added and mixed for an additional 6 minutes. The resultant explosive composition was tested in a 1%" x 16" cartridge (unconfined) and was not detonated by a No. 6 electric blasting cap. The cartridge was detonated by a 0.25 lb. booster and the unconfined detonation velocity was 12,000-13,000 feet per second. The rate of detonation confined was 15,000-16,000 feet per second. The

density of the product was 1.52 grams/cc. The water resistance of the product was rated as excellent.

EXAMPLE 3 An explosive powder composition is prepared as follows:

No. l nitrocotton (0.3 lb.) is mixed with ethylene glycol (1.2 lbs.) and water (0.3 lb.) for 1 minute. The mixture and nitroglycerine (11.0 lbs.) are mixed for about 4 minutes to form a relatively uniform thick gel. The nitroglycerine used is a nitrated mixture of 65% ethylene glycol and 35% glycerine.

A dope mix is prepared by intimately admixing the following ingredients.

Ingredient: Lbs. Ammonium nitrate 58.5 Sodium nitrate 19.0

Starch 1.5 Microballoons (very small hollow resin balloons) 0.2 Guar gum 3.0 Calcium stearate 0.5

Chalk 0.5

All of the dope mix is added to the 12.8 lbs. of the thick gel prepared as described above and is then mixed for 1 minute. 2.0 lbs. of fine aluminum powder is then added and mixed for three minutes. 2.0 lbs. of No. 15 encapsulator grade oil is then added and again mixed for 2 minutes.

The resultant explosive powder shows good water resistance.

I claim:

1. In a process for the preparation of an explosive composition containing nitrocellulose and an explosive nitric ester wherein the nitrocellulose and explosive nitric ester are mixed with ammonium nitrate and sodium nitrate ingredients of the explosive composition, the improvement comprising mixing (a) nitrocellulose with (b) a liquid dispersing agent selected from the group consisting of ethylene glycol, glycerine and mixtures thereof, and thereafter mixing the resultant mixture with (c) an explosive nitric ester.

2. A process for preparing an explosive nitric ester gel which comprises mixing (a) from about 0.5% to about 3.0% by weight of nitrocellulose with (b) from about 5% to about 15% by weight of a liquid dispersing agent selected from the group consisting of ethylene g1ycol, glycerine and mixtures thereof, and thereafter mixing the resultant mixture with (c) from about to about by weight of an explosive nitric ester, to gel said explosive nitric ester, said weight percents based on the weight of said explosive nitric acid gel.

3. The process of claim 2 wherein (c) said explosive nitric ester is nitroglycerine.

References Cited UNITED STATES PATENTS 1,640,712 8/1927 Moran 149-95 1,686,952 10/1928 Brown 149-95 1.879.064 9/1932 Bryan 149-95 1,966,090 7/1934 Fassnacht 149-95 2,146,026 2/1939 Power et a] 149-95 X CARL D. QUARFORTH, Primary Examiner S. J. LECHERT, JR., Assistant Examiner US. Cl. X.R. 149-95 

